[Cardiovascular diseases and lipid abnormalities in Cushing's syndrome]. / Manifestations cardiovasculaires et anomalies lipidiques au cours du syndrome de Cushing.

The present study involved 143 patients with confirmed Cushing's syndrome, including 100 with Cushing's disease, 20 with adrenal adenoma and 23 with adrenal carcinoma. Out of 120 assessable patients 68% had arterial hypertension and the majority of these (78%) presented with adrenal carcinoma. Blood pressure returned to normal in 85% of hypertensive cases after Op'DDD therapy or adrenalectomy. Excessive cortisol production is probably the main cause of hypertension, but the precise pathophysiological mechanism is controverted. Serum lipids were studied in 88 patients, 40% of whom were found to have combined hyperlipoproteinaemia, this abnormality being particularly frequent in patients with malignant adrenal tumour. Serum cholesterol levels returned to normal after adrenalectomy. However, they were further increases during Op'DDD treatment (p less than 0.01) and only became normal after withdrawal of the drug. Cerebral vascular accidents were uncommon (6%) and might have been due to cobalt irradiation of the hypothalamus-pituitary region.

Initial rate of cholesterol esterification association with high density lipoproteins in human plasma.

The enzyme lecithin:cholesterol acyl transferase has been measured both in total plasma and in the fraction of plasma from which very low and low density lipoproteins have been removed by ultracentrifugation. The correlation between the activity of the enzyme and the free cholesterol concentration was positive in whole plasma and negative in apoB-deficient plasma. On the other hand, the positive correlation between plasma triglycerides and cholesterol esterification was not changed by the removal of apoB-containing lipoproteins. Subjects with the highest levels of high density lipoprotein cholesterol were found to have the lowest enzyme activity, but this correlation was disclosed only in apoB-deficient plasma. This inverse relationship was abolished when the enzyme activity was measured in the absence of all lipoproteins with a density less than 1.125 g/ml. Cholesterol esterification, when determined after removal of lipoproteins with a density less than 1.063 g/ml, was negatively correlated with the in vivo plasma concentration of lipoproteins in the density range 1.063-1.125 g/ml. The same results were obtained in vitro by addition of increasing amounts of this class of high density lipoproteins either in total plasma or in the ultracentrifuged fractions of plasma. This provides further evidence that the lighter density class of high density lipoproteins inhibits the enzyme reaction under physiological conditions.

Apolipoprotein of the low density lipoprotein of human plasma: structural study in familial hyperbetalipoproteinemia.

Isolation of the low density lipoprotein (LDL) from human plasma was accomplished within a narrow density interval (1.030-1.045 g/ml). After covalent modification by maleic anhydride of the protein moiety and delipidation it was possible to fractionate, by ion-exchange chromatography, up to 35% of the protein into three peptides with distinctive amino acid compositions. These fractions appeared to be identical in normal individuals and in patients with familial hyperbetalipoproteinemia (FH). Our findings provide further evidence that in FH the abnormal catabolism of the protein moiety of LDL is not related to a modification of its structure.